With development of a mobile communications network (a standard is formulated by the 3rd Generation Partnership Project (3GPP)) and a wireless local area network (WLAN), interworking and integration of the two networks receive increasing attention from an operator. In order to implement interworking and integration of a 3GPP access network and a WLAN access network, the 3GPP standardization organization specifies a standard for interworking between the 3GPP access network and the WLAN access network, and defines access network discovery and selection function (ANDSF). The ANDSF provides an access network discovery and selection policy (ANDSF Policy) to a user equipment (UE), and the UE may discover and select a WLAN or 3GPP access network according to the ANDSF Policy so that a part of a data stream accessed through the 3GPP access network is offloaded to the WLAN access network, and offloading of a data stream may also be performed from the WLAN access network to the 3GPP access network so as to prevent network congestion.
However, in a roaming scenario, a case in which the UE simultaneously attaches to (that is, registers with) two different public land mobile networks (PLMN) through the WLAN access network and the 3GPP access network may occur. For example, the UE attaches to a first visited public land mobile network (VPLMN) of an operator 1 using a 3GPP access point 1, and meanwhile attaches, using a WLAN access point 2, to a second VPLMN of an operator 2 or to a home public land mobile network (HPLMN) of an operator to which the UE subscribes. After attaching, the UE may receive an ANDSF Policy from the first VPLMN, and an ANDSF Policy from the second VPLMN or the HPLMN.
Because ANDSF Policies sent by different PLMNs are different, in the roaming scenario, the UE cannot select an access network according to different ANDSF Policies sent by different PLMNs. As a result, a data stream of the UE cannot be offloaded between different access networks of the PLMNs, thereby causing network congestion.